now they are even getting better looking.
i agree with winter waterproofing is a good idea, also you could try rubbing out the marks. use some lexol conditioner take a smooth spoon put your hands inside and rub the marks. this should create some heat with the leather and allow the oils to fill and smooth the scuffs. maybe even take some clear dry wax if you have and very lightly apply on the scuffs and rub with the spoon. the point is to to get the grain to lay flat. after this apply the waterproof.
i don't think i would use any dye unless you know the exact color and like i said the scuffs add character. but at least you could smooth the grain.